1. Field of the Invention
This invention relates generally to an apparatus for conducting a bronchial electrocardiogram, and more particularly to an intrabronchial catheter of a bronchial electrocardiographic apparatus, which is inserted into the trachea or bronchus of a human body and is provided at the leading end portion thereof with a balloon having electrocardiographic lead electrodes, capable of being inflated within the trachea or bronchus of the human body so as to bring the lead electrodes internal close contact with the internal surface of the trachea or bronchus.
2. Description of the Prior Art
An electrocardiogram is essential to diagnose possible heart disorders such as arrhythmia and ischemia. Body-surface electrocardiography which is the most popular electrocardiography practiced at present, transesophageal lead electrocardiography capable of precisely diagnosing the cardiac function, intracardiac lead electrocardiography, and intrabronchial electrocardiography are well known.
As also known, in body-surface electrocardiography, electrocardiographic (ECG) lead electrodes are located at anatomically prescribed locations (usually, twelve regions) on the surface of the human body in order to detect an ECG lead current generated by the heart. This medical method is convenient because it can be easily effected by merely attaching the ECG lead electrodes to the surface of the human body. However, since the ECG lead electrodes are positioned at the locations far from the heart, the ECG lead current cannot sufficiently be detected. Particularly, this medical method is not applicable for searching for a location where there is a cardiac insufficiency.
The transesophageal lead electrocardiography is effected by inserting a catheter provided at its leading end portion with ECG lead electrodes into the esophagus through the oral cavity or nasal cavity and bringing the lead electrodes into contact with the internal surface of the esophagus so as to detect the ECG lead current. This medical method enjoys an advantage in that the lead electrodes can be positioned near the heart, especially, the posterior wall of the left atrium of the heart, thereby obtaining more reliable cardiac information compared with the aforenoted body-surface electrocardiography. However, this medical method demands skill in inserting the catheter into the esophagus and attaching the lead electrodes to the internal wall of the esophagus. Accordingly, this medical method cannot easily be practiced.
On the other hand, the intracardiac lead electrocardiography uses a catheter with ECG lead electrodes which is introduced into the heart through thick blood vessels and secured onto the internal wall of the heart in order to directly pick up a lead current. Thus, this is looked on as a medical method capable of obtaining the most precise cardiac information. However, this medical method entails a disadvantage in that it cannot easily be effected since it requires remarkably high-level surgical skill for inserting the catheter with the lead electrodes into the heart while X-ray the human body to secure the lead electrodes onto the anatomically prescribed locations in the heart with high accuracy.
In the intrabronchial electrocardiography similar to the transesophageal lead electrocardography, a catheter with ECG lead electrodes is inserted into the trachea or bronchus instead of the esophagus to detect the ECG lead current from the trachea or bronchus. This medical method is effected by positioning the ECG lead electrodes mounted on the leading end portion of the catheter at the bifurcation or the internal surface of at least one of the left and right bronchi in order to detect the ECG lead current near the heart. This intrabronchial electrocardiography also suffers a disadvantage in that, although an X-ray is conducted when inserting the lead electrodes into the trachea and bronchus, the lead electrodes disposed on the leading end portion of the catheter cannot easily be secured in position at the anatomically prescribed locations in the trachea or bronchus. The fact of the matter is that the catheter can be inserted into the trachea with relative ease because the trachea is hollow at all times, whereas the work of stably positioning the lead electrodes at the optimum locations in the trachea or bronchus often becomes much harder and more time-consuming, and moreover, possibly entails the risk of causing a patient pain. Under these circumstances, this medical method is scarcely available clinically.
As noted above, various medical methods for obtaining an electrocardiogram have been so far proposed and applied practically, but as is also apparent from the foregoing, body-surface electrocardiography makes it impossible to obtain precise cardiac information for diagnosing possible heart disorders, and transesophageal electrocardiography, intracardiac electrocardiography and intrabronchial electrocardiography disadvantageously call for high-level surgical skill and specific medical equipment and the task of inserting the lead electrodes which consumes much time and labor. However, a need has been earnestly felt for easy and reliable electrocardiography capable of obtaining precise cardiac information useful for making a diagnosis of heart disorders such as arrhythmia.
In light of the present circumstances, the inventors of this invention have studied intrabronchial electrocardiography and eventually developed new intrabronchial electrocardiography capable of being practiced easily and reliably.
As described above, conventional intrabronchial electrocardiography suffers from the defect that the lead electrodes cannot easily and stably be positioned at the anatomically prescribed locations in the trachea or bronchus. In particular, although the lead electrodes should be kept in close contact with the internal surface of the trachea or bronchus in order to obtain a precise electrocardiogram, the conventional intrabronchial electrocardiography has not employed means for stably retaining the lead electrodes at the suitable locations on the internal surface of the trachea or bronchus for effectively picking up the ECG lead current. Moreover, it is unacceptable to dislocate the lead electrodes in the trachea or bronchus, and thus, there has been a great need for a safe, reliable and handy intrabronchial catheter which can be suitably applied to intrabronchial electrocardiography and has ECG lead electrodes capable of being secured reliably at the anatomically prescribed locations in the trachea or bronchus.